1. Technical Sphere
The invention relates to a safety device and a safety procedure in the case of a tipping dump body of a truck. The dump body is tipped generally by means of two hydraulic lifting cylinders. The invention is especially intended for use in waist-controlled trucks (articulated haulers), but can advantageously also be adapted to other trucks provided with tipping dump bodies or other types of tipping flatbed.
2. Background
Normally, by operating a control in the driver""s cab of the vehicle, a tipping dump body of the aforementioned type can be made to assume a so-called floating position, in which the lifting cylinders are not pressurized and the dump body is free to turn about its tipping center. The floating position is used partly during transport with the dump body resting, with unpressurized lifting cylinders, against the vehicle chassis frame in order to transmit the line of forces downwards from the dump body to the chassis frame in the most advantageous way possible. This floating position is also partly used when the dump body is loaded in such a way, or is in such a position, that it can be lowered from the raised position to the transport position under its own weight and without the action of the lifting cylinders. Where necessary, however, the driver can also lock the dump body in a so-called holding position in which the lifting cylinders are pressurized by means of valve elements in such a way that the position of the dump body is locked in any desired position.
One problem with conventionally designed trucks of this type is that the dump body is allowed to assume the floating position even when the driver is out of the vehicle driver""s cab and thereby no longer has control over the dump body. In this situation, for example, a strong gust of wind may cause the xe2x80x9cfloatingxe2x80x9d dump body to slowly start to turn about its tipping center and to be lowered, uncontrolled, onto the chassis frame, resulting in material damage.
The aforementioned problem(s) are overcome via the safety arrangement and procedures of the present invention(s). In an exemplary embodiment, the invention takes the form of a safety device in a tipping dump body of a truck in which the dump body, through the operation of a control in the driver""s cab of the vehicle, and by means of at least one preferably hydraulic lifting cylinder, is designed to be moved between a lowered transport position and a raised tipping position. A floating position is also accommodated in which the lifting cylinder is not pressurized, as is a holding position in which the lifting cylinder is pressurized and the position of the dump body is locked. In the example, the device has the characteristics of a detector that is designed for detection of the driver""s presence in, or absence from, the driver""s cab. Via this device, either a presence signal or an absence signal is delivered to a controller depending on whether or not the driver is in the driver""s cab. Preferably, the control is designed, in the event of an absence signal from the detector, to assume the holding position.
The invention also relates to a safety procedure for the operation of a dump body of a truck in which the dump body, through the operation of a control in the driver""s cab, and by means of at least one preferably hydraulic lifting cylinder, is moved between a lowered transport position and a raised tipping position. In this aspect of the invention, the procedure further permits the dump body to assume a floating position, in which the lifting cylinder is not pressurized, and to assume a holding position in which the lifting cylinder is pressurized and the position of the dump body is locked. An exemplary procedure according to this aspect of the invention includes the characteristics of a detector that detects the driver""s presence in, or absence from, the driver""s cab and delivers either a presence signal or an absence signal to the control depending on whether or not the driver is in the driver""s cab. The control is configured to, in the event of an absence signal from the detector, assume the holding position.
In summary, the several aspects of the present invention(s) provide a safety system and method that simply and cost-effectively eliminates, or at least reduces, the risk of uncontrolled lowering of the dump body as a result of the dump body being in the floating position when the driver leaves the driver""s cab.
Other special features and characteristics of the invention are described in more detail below.